Proposed work will concentrate on three areas: 1) Development of methods for the exposure of ventricular arrhythmias through the use of abbreviated and alternative exercise protocols, the employment of psycologic stress testing and the optimization of monitoring periods for asymptomatic populations at high risk for coronary heart disease; 2) Continued study of new antiarrhythmic drugs and the relationship of efficacy of acute drug testing to results of chronic therapy: and 3) Determination of the significance of ventricular premature beats as they relate to life events and various psychologic stress.